In order to inspect the quality of conductive patterns formed on a circuit board, the presence of disconnection in the conductive patterns has been checked by bringing a signal supply probe located on one of the sides of the circuit board into contact with one of the ends of the conducting pattern to be inspected (hereinafter referred to as “target conductive pattern”), supplying an inspection signal from the signal supply probe to the target conductive pattern, and detecting the inspection signal from a sensor probe which is located on the other side of the circuit board and in contact with the other end of the target conductive pattern. In this case, if the sensor probe detects the inspection signal, it will be determined that the target conductive pattern is normal or in a conductive state. If not, it will be determined that the target conductive pattern is abnormal or in a disconnected (open) state.
In conjunction with the inspection on disconnection performed by supplying an inspection signal from one end of the target conductive pattern and detecting the inspection signal from the other end of the target conductive pattern, the presence of short between the target conductive pattern and the conductive pattern adjacent thereto has also been checked by determining if the inspection signal is detected from another sensor probe in contact with the other side's end of the adjacent pattern.
In the above conventional technique, the direct contact between the pattern and the probe causes the molecular transfer therebetween and/or scratches on the pattern, which have an adverse affect on the performance of the circuit board. Minute dusts also cause insufficient contact between the probe and the pattern, which is likely to lead to a defective inspection result such that disconnection is erroneously detected even in a normal pattern.
Further, if the shape of the circuit board is distorted due to temperature variation, it will be extremely difficult to perform an adequate probing operation, resulting in occurrence of detection errors.
Furthermore, in the conventional technique, the short between adjacent conductive patterns can be checked only if an inspection signal is supplied to only a specific conductive pattern while arranging the sensor probes in their predetermined positions. This leads to complexity in structure and inspection process.
In view of the above problems, it is therefore an object of the present invention to provide a circuit-pattern inspection apparatus and method capable of reliably inspecting a parallel array of conductive patterns in a simple structure and inspection process while minimizing constraining factors in supplying an inspection signal to the conductive patterns.